what is wrong with my thermostat?

[mrsimpkins]

ok i woke up this morning and went to turn the heat up. my thermostat is not working. it is digital no lights no numbers. if i push the reset button numbers come up for a second, but no light. it is a lennox51m33. i checked the breaker it isn't flipped.
my husband is in meetings all day as soon as he gets home we are going out of state until sunday evening.
it is going to be very cold here the next several nights, don't want the pipes to freeze and bust.

if any one could help i would be ever so grateful!

[Clanad]

The power supply to these types of thermostats, at least here in the U.S. is supplied by the standard (in our case 120v) house current, however it's stepped down, again in our case to 24 volts. This step down device, usually called an inverter or transfomer, is small and often built into the back of the case. Alternately, the most common brand here in the U.s. is built by Honewell and uses two AAA batteries to power the display. These are also held within the case. These are normally what fails when the display disappears. The case is easy to pop off, but use care. There should be no dangerous voltage to the unit and you may find batteries that need replacing. If it's a failed transformer it'll have to be replaced by a service guy... Best of luck!

[TWR]

Hi, Every chance the Pilot light has gone out, Check the Inspection window within you boiler you should see a flame. T.W.R.

[Clanad]

I further see the model number of the Lennox unit here:
http://www.hvac-direct.com/pdf_files/homeowner /504931a.pdf...

That unit indicates, by model number, that you have a heat pump... the compressor outside of the hosue that also powers the air conditioning. If that's true, there'll be a switch on the top or side of the unit labeled EMG (emergency... move that the switch to that position and the unit should power up. Additionally, it appears that you live here in the U.S. (going out of the state), in which case, you're likely to have a a back up heat source such as a gas or propane furnace or electric auxillary heat built into the system The system should have a switch, probably near the furnace installation in your basement, that can be moved to the back up system. If, for some reason, moving the thermostat switch to EMG doesn't solve the problem, look for the heat source switch I've described... (By the way, this is a United KIngdom site based somewhere in England so sometimes one doesn't get the response one needs... other times one gets entirely too much in the way of response...)

[gasman]

Not so sure about U.S. systems but here in th U.K. usually when the display and backlight goes out there is a power problem. You say you have checked the breaker and it is fine but also it is normal here in England anyways to have an inline 3amp fuse somewhere between the breaker and the unit to protect it. If this is so you may need to simply change the fuse. The batteries are just a power back up to keep the time and programme memory from deleting in the event of a power failure but they will not activate the heating.